diff --git a/css/files.scss b/css/files.scss
index 01bab0874..d05fa7b46 100644
--- a/css/files.scss
+++ b/css/files.scss
@@ -23,7 +23,7 @@
 	opacity: 1;
 }
 
-#richdocumentsframe {
+.office-viewer__iframe {
 	background-color: #fff;
 	width:100%;
 	height: 100vh;
diff --git a/css/mobile.css b/css/mobile.css
index c7ef3151e..8195d7fd8 100644
--- a/css/mobile.css
+++ b/css/mobile.css
@@ -15,7 +15,7 @@
 		padding-top: 0;
 	}
 
-	#richdocumentsframe {
+	.office-viewer__iframe {
 		height: 100%;
 		position: fixed;
 	}